I'm configuring my Akka application to use the SLF4J logger as specified here:
http://doc.akka.io/docs/akka/2.3.4/scala/logging.html
Underneath the hood, I'm depending on Logback to do the logging. I'm developing a common module for logging purposes that users can use in their actor systems. Mainly, I'm creating a trait they can mixin.
I have a trait that does this:
I have something as such:
trait ActorLogger {
val log: DiagnosticLoggingAdapter = Logging(this);
}
I have some extra logic which will add MDC values to the DiagnosticLoggingAdapter's MDC. The problem is now this: I expose a different logger entirely if users want to mixin to their non-actor classes. So I might have something like this:
trait ClassLogger {
val log = LoggerFactory getLogger getClass.getName
}
I want the MDC values to carry over to this logger. So for example, if I put MDC values into my DiagnosticAdapterLogger, I should expect to be able to get those values from org.slf4j.MDC
How can this be achieved in a clean way?
Thanks!
If all your code outside the actor system is single-threaded (i.e. you don't spawn any additional futures or threads), there's a simpler solution than the one @jasop references.
I have this mixin that takes care of populating the MDC both inside and outside actors:
import akka.actor.DiagnosticActorLogging
import akka.contrib.pattern.ReceivePipeline
import org.slf4j.MDC
import scala.collection.JavaConverters.mapAsJavaMapConverter
trait MdcActorLogging extends DiagnosticActorLogging {
this: ReceivePipeline =>
/**
* This is for logging in Akka actors.
*/
override def mdc(message: Any): akka.event.Logging.MDC = {
message match {
case MyMessage(requestId) => Map("requestId" -> requestId)
case _ => Map()
}
}
/**
* This makes the MDC accessible for logging outside of Akka actors by wrapping the actor's
* `receive` method.
* Implements the [[http://doc.akka.io/docs/akka/2.4/contrib/receive-pipeline.html ReceivePipeline]]
* pattern.
*/
pipelineOuter {
case e @ MyMessage(requestId) =>
val origContext = MDC.getCopyOfContextMap
val mdcWithPath = Map("requestId" -> requestId,
// inside actors this is already provided, but outside we have to add this manually
"akkaSource" -> self.path.toString)
MDC.setContextMap(mdcWithPath.asJava)
ReceivePipeline.Inner(evt) // invoke actual actor logic
.andAfter {
if (origContext != null)
MDC.setContextMap(origContext)
else
MDC.clear()
}
case e => ReceivePipeline.Inner(e) // pass through
}
}
The non-actor code can use any logger, e.g. mix in the com.typesafe.scalalogging.LazyLogging
trait.
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